mri only radiation therapy with cpap

Conditions: Carcinoma Liver; Carcinoma, Pancreatic

Summary: the goal of this imaging study is to evaluate and improve the treatment planning techniques for abdominal radiation therapy. to accurately treat a tumor with radiation, computed tomography (ct) and magnetic resonance images (mri) are used to distinguish a tumor from normal, healthy tissue. however the quality of these images can be distorted by motion from breathing. to decrease motion, a patient may be asked to hold their breath or compress the abdomen, but currently there is no standard or best management option for all patients. this study will explore the use continuous positive airway pressure (cpap), a pressurized breathing mask, during mri or ct imaging to decrease motion in the abdomen and produce higher quality images. with these additional images, we will also explore the feasibility of creating treatment plans using the cpap mri images alone.

patients will undergo both ct and mri prior to abdominal radiation therapy and cbct and orthogonal kv/mv images prior to each treatment delivery. a two arm study will be performed and patients will be enrolled into a given arm according to their eligibility. arm 1 is for patients that are either not eligible for cpap or that are unable to tolerate cpap. these patients will undergo breath-hold and 4d imaging for both ct and mri without cpap. arm 2 is for patients that are eligible for cpap and able to tolerate cpap. these patients will undergo breath-hold ct without cpap, 4d-ct with and without cpap and 4d-mri with cpap. two specific aims will be investigated. in aim 1, we will explore the feasibility of using a mri-only in radiation oncology workflow. a probabilistic classification method will be utilized to generate a pseudo-ct from mri to support treatment planning and image guidance for radiation therapy. the quality of the pseudo-ct will be evaluated by comparing it with ct. in addition, the reverse mapping will be investigated to create pseudo-mri from cbct to improve visualization of treatment targets and soft tissue prior to treatment delivery. in aim 2, we will evaluate the utility of cpap as a novel motion reduction methodology for patients with liver and pancreas cancer, to this end ct images with and without cpap will be used. the evaluation will be based on the changes of motion magnitude, the achievable volumetric reduction in treatment target volumes, and doses to the targets and critical organs.

Eligibility criteria:
inclusion criteria: * patients have liver or pancreas tumors (either primary tumors or metastases) and are scheduled to be treated with radiotherapy (either 3d conformal or intensity-modulation radiotherapy (imrt) with conventional or hypo- fractionation). * kps \> 70 * if a biopsy is performed, the patient is at least 1 week post-biopsy. * the patient's age must exceed 18 years. * the patients must be able to commit to t1-weighted, t2-weighted, dixon fat and water, ultrashort-te, and other clinical or research mr sequence images prior to treatment. * cpap eligibility: cpap is a safe, effective form of therapy with rare complications. relative contraindications include patients with bullous lung disease, fibrotic lung disease, claustrophobia and recurrent sinus or ear infections. the absolute contraindications include obtundation /unconsciousness, chest wall trauma, suspected pneumothorax, persistent nausea/vomiting, active upper gi bleeding, history of recent gastric surgery, facial anomalies/trauma \[15,16\]. if there is any question about the above history and medical problems, the subject will be referred to a pulmonologist for consultation. * the patients with above contraindications are not cpap eligible and are enrolled in arm 1 for the protocol without cpap * the eligible patients are enrolled in arm 2 for the protocol with cpap. exclusion criteria: * any medical condition, which would make the imaging studies unsafe or poorly tolerated * known allergic reaction to contrast or shellfish * implanted metal devices or foreign bodies that serve as a contraindication to mr imaging * creatinine \> 1.4 mg/dl and creatinine clearance \< 20 mg/dl. * uncontrolled, clinically significant cardiac arrhythmias * severe claustrophobia * pregnant female * kps \<70